Galium prattii apparently is endemic in Sichuan. It is often so close to forms of the reddish-purplish flowering G. blinii that only the longer lanceolate leaves, the more flower-rich cymes, and the white to greenish flower color of G. prattii help to separate them. Otherwise, G. prattii seems to link G. asperifolium and G. tokyoense. From the first it differs by less-bracteate inflorescences and less-acuminate corolla lobes, from the second by its leaves, which are lanceolate and apically more gradually narrowed (vs. subspatulate and apically rounded, mucronate).